The present invention relates to the manufacture of rubber tires. It is known that the manufacture of tires comprises, in general, preliminary steps for the preparation of semi-finished products and always includes steps for the assembling and vulcanization of the tire.
The assembly of the tire consists in superimposing the different components of the tire in a suitable order, defined by the architecture of the tire, so as to obtain what is known as a raw tire. The purpose of the vulcanization is to fix the tire in its final shape. For this, a mold of suitable shape is used and the raw rubber is subjected to a certain molding pressure, far greater than atmospheric pressure, while the heat necessary for the vulcanization reaction by an increase of the temperature of the raw rubber is imparted to the latter.
For this, a vulcanization law is employed which the person skilled in the art has little trouble in establishing and which is expressed by a given period of time during which the tire to be vulcanized is held at a given temperature level, generally constant, while keeping it under pressure in order to avoid the presence of bubbles of gas within the rubber and in order to assure a perfect molding of the final manufactured shape.
Tire manufacturing factories have shops dedicated to the assembling of tires, the role of which is to produce raw tires, as well as shops dedicated to the vulcanizing of the raw tires. This results in travel of the raw tires between shops, which travel is responsible for a substantial in-process inventory. U.S. Pat. No. 4,877,468 discloses an organization for just in time flows between the different tire manufacturing shops. However, in as complex an installation as the manufacture of tires, the production of such an installation remains extremely sensitive to breakdowns affecting only one phase thereof. Industrial practice has shown that it is necessary to have buffer stocks in order suitably to take care of transitory failures of a complicated production tool.